1.
Perhaps the Fire Lions were too powerful for Foul to eliminate. There are rumors in earlier books of the Fire Lions and the skurj battling on Mount Thunder. So perhaps he was trying.

2.
Because Foul held something back as a last-ditch effort to prevent them from entering Mount Thunder. And he had to use forces which could guard the front door but run to the back door if necessary.

Also, we have to think about what his goals might have been. He may not necessarily have been trying to kill his opponents, only slow them down. Surely he had seen that, with their having two rings and a Staff, he didn't have much chance in stopping them completely._________________* I occasionally post things on KevinsWatch because I am a fan of Stephen R. Donaldson; this should not be considered as condonation of the white nationalist propaganda for which this forum has become a platform.